Dual-cycle cam grinding machine with electrical pulse operated wheel feed

ABSTRACT

Improved dual-cycle camshaft grinding machine, method of operation thereof, and improved wheel feed control sub-assembly therefor with a grinding wheel feed driven by an electrohydraulic pulse motor regulated by open loop numerical control. Solid state machine logic regulates the initiation of open loop wheel feeding steps and controls related machine functions. Hand control for purposes of calibration setup is accomplished through the automatic controls eliminating the redundant handwheel and like manual controls of the art.

[ 5] Mar. 19, 1974 United States Patent [191 Wespi DUAL-CYCLE CAMGRINDING MACHINE 3,665,652 5/1972Gordon............................5l/l65.77

WITH ELECTRICAL PULSE OPERATED WHEEL FEED Primary Examiner--Harold D.Whitehead [75] Inventor:

George E. Wespi, Holden, Mass.

ABSTRACT Filed:

Improved dual-cycle camshaft grinding machine.

Related Application Data method of operation thereof, and improved wheelContinuation-impart of Ser. No. 60,288, Au feed control sub-assemblytherefor with a grinding 1970, Pat. No. 3,70l,220.

wheel feed driven by an electro-hydraulic pulse motor regulated by openloop numerical control. Solid state machine logic regulates theinitiation of o pen loop [52] US. 51/101 R, 5l/l65.77, 51/l65.9l

Int. B24b 19/12 wheel feeding steps and controls related machinefunctions. Hand control for purposes of calibration [58] Field ofSearch......... 5l/l01 R, 165 R, 165.77,

setup is accomplished through the automatic controls eliminating theredundant handwheel and like manual controls of the art.

References Cited UNITED STATES PATENTS l l/l971 3,622,287Kurimoton........................ 51/165 R 11 Claims, 15 Drawing FiguresCRIIII 4 MW WW M lwv m a a 5:. l IIQ m S m a P M. Q I H h m lm 3 2 L .HNE ,..+mHm J ri x a r a lllll m a; 1...; W x ,cz CW- c R G m w c q. a r a1 at. m w m A M IN. L |.|ll I l l i ill l||||| l 7H3 c .F. [Y ll 0% 7 Jl l I I I I I I I l U u w M 3 IL i W 7 3 L m 1 V H Elana DRO PATENTEBIMR I 9 I974 sum 01 or 14 PATIZNTEIJMAR 19 I974 sum '02 [1F 14 Pmmmmw m43791.176

SHEET us nr 14 WORK DRIVE]? C2 BEN Q K578 K003 WCI (B) ss-z Kl23 K615 7MWORK JOG 0O PB|2 DI ss-z ' HAND cos CONTROL/3 M M N F/G.5 -L APATENTEDNAR I 9 I974 LAST CAM FIG.

' saw "us 0F 14 Al u K4 I L B5 LAST CAM D07 05 WORK REJECT -ABORT K LK003 CYCLE D08 Kl23 Fl ..B5 c4 H5 K L LAST K003 J3 CAM u HI H ROBAR 5 DoBACK V 4 K|23 L K Al WORK F J REJECT H KOO F2 T v WORK ROTATION l8 SOLPmmmnmsuu A 8797.176

sum '07 HF 14 GAGE SISTEM 4 3 l2 I7 I I A N N n/ I k L K003 Kl34 FSFS-FWD u T N M. SAFETY WWNLOAD V 5 E03 K6I5 GAGING E3 K578 POSN. 5 H I M7 V U'| k.) LS|4 GAGING NOT IN PROGRESS WORK REJ. N M

FOOTSTOCK OVERTRAVEL SIGNAL KI 34 C5 WORK NOT REJE F K003 B5 AUTO CYC. H

SP ROT'N.A| RB BACK Hl F5 FORWARD WORK TABLE Fl INDEX M25 K6I5 4A SOLKI34 F D F K6l5 M 44E. F3 {D6 WORK TABLE N REVERSE Pmmmnmswu 3.797.176

' SHEET '08 HF 14 CUSHION PLUNGER DOWN L KI24 FEED SCREW H OVER TRAVELLIMIT D5 FINE AB/HANDW E' E FEED J K FORWARD /AuTo- M J N2- K4 "H NBACK-. LASH TIMER AUTO SLOW FINISH Jl AZ RESET ELEC. FEED ON E K782 F/G.J4 F 5 Su DE REAR Pmmmm I 9 1914 3.797; 176

sum *12 0F 14 MACHINE l2 l7 LOG m 3 4 Fl G8 4 I PULSER LS2 UNLOAD TIMINGss-z ROUGH CYCLE PULSER ISH CYCLE FINE FEED SLIDE REAR DUAL-CYCLE CAMGRINDING MACHINE WITH ELECTRICAL PULSE OPERATED WHEEL FEED BACKGROUND OFTHE INVENTION Camshaft grinding machines have been used by theautomobile industry and related industries for almost half a century.These machines have it in common that a camshaft blank is mounted inline with a master cam assembly and a grinding wheel is fed into thecamshaft blank to grind various cam positions thereon to the desired camconfigurations. The master cam and camshaft blank rotate together withthe master cam rotating against a fixed follower causing displacement ofthe camshaft blank so that the desired cam surface is generated by acircular grinding wheel. The state of this art is exemplified by U.S.Pat No. 2,786,311 to Hill et al. granted Mar. 26, 1957 and in subsequentimprovements made to such apparatus including a double stop mechanism toafford dual cycle capability. As can be seen in the Hill patent, thecamshaft blank master cam assembly is mounted on a rocker bar whichpivots the assembly to and from the grinding wheel and includes apivoted position wholly away from the grinding wheel to allowlongitudinal displacement from one cam to the next without interferenceby the grinding wheel or master cam follower. The grinding wheel is fedinto the cam when grinding, retracted to a starting point, and fed inagain. The grinding cycle consists of a rough cycle with high wheel feedspeeds and a finish grinding cycle with a slower feed rate to finish offa given cam surface. The rough grinding steps are done on all cams firstand then the finish grinding steps are done on all cams. i

Closed loop controls are commonly used in connection with wheel feed,with positive mechanical stops arresting in-feed movement of a grindingwheel into the work, the stop or stops being set according to the amountof stock to be removed from the cam shape being ground. Open loopcounter controls are utilized in connection with work rotation schedulesin camshaft grinding machines and have been used in connection withwheel feed schedules in some grinding machines but not in wheel feedcontrol for camshaft grinding machines.

The relative advantages and disadvantages of open loop control andclosed loop control are well known as a matter of general automaticcontrol theory. The open loop system affords greater protection againstthe danger of instability development; it can generally be tuned withgreater accuracy than a closed loop feedback control (such as themechanical stop noted above); and can, in some cases, be less sensitiveto variations arising from changing ambient conditions, machine wear,etc. Implementation of open loop feedback control of wheel feed incamshaft machines is however made difficult by the inability of the artto deal with the problems of loss of input counts of wheel feed. Therehas been no practical way, short of superimposing a closed loop systemon the open loop system to deal with the problem. Another problem isthat of overlooking a preset wheel feed stop reference due to noise andother causes-External limit switches and the like prevent a disastrousaccident when this occurs, but the work is spoiled.

The continuing development of such machine tools, has been paralleled bythe continuing requirement for controlled displacement of movablymounted machine elements, and especially for satisfactory means offeeding and retracting the movably mounted elements of machine toolswhich support various forms of cutting tool elements, such as grindingwheels incorporated in various types of cylindrical grinders such as thegrinding machine described and illustrated in the above cited Hill etal. patent as well as in Hill U.S. Pat. No. 3,171,234 and in machineswhich comprise multiple grinding wheels arranged to grind crankshaftmain bearings, and the grinding machine as described and illustrated inMader, U.S. Pat; No. 2,723,503, including workpiece supports arranged tosupport a crankshaft for grinding its crankpin bearings.

Comstock U.S. Pat. No. 2,867,759, describes a grinding machine in whichthe grinding wheel feed includes a feed screw rotated by a servo-motoractuated by an electrically operated precision control and positionindicating system, and Morgan, Jr. et al, U.S. Pat. No. 3,056,240describes several features of an automatic grinding machine, among thema wheel feed including an hydraulic paddle motor to provide a fixedrapid feed and an hydraulic rotary motor the speed and direction ofrotation of which are determined by operation of an electro-hydraulicservo-valve controlled from a control station provided with a hand wheeleither manually rotated for manual control of wheel head movement, orrotated by a control motor in automatic grinding cycles.

Eyler, U.S. Pat. No. 3,121,831, describes an automatic control systemfor positioning a movable member comprising a null-balance systemincluding first and second differential transformers, a drive motor anda pilot motor all so inter-connected operation of the pilot motordisplaces the elements of the first differential transformer from theirnull position as it operates .to restore the elements of the seconddifferential transinitiate another incremental feeding movement.

Dunn, U.S. Pat. No. 3,309,820, describes a grinding machine equippedwith opposed grinding disks, each mounted for feeding movement toward,and retraction from, a workpiece grinding position by a feed mechanismincluding an electric stepping motor actuated by a stepping switch andan electrical control semiautomatically operative to produce a number ofincremental feeding movements determined by the setting of an adjustablecounter relay, and alternatively manually operable to produce repeatedincremental movements.

In addition to the electrically operated and/or actuated feed mechanismsdescribed in the several prior patents referred to above, Price, US.Pat. No. 3,466,976, describes a cylindrical grinding machine equippedwith a well-known type of wheel feed mechanism including a feed screwand actuating means therefore to produce successively a rapid feed, agrinding feed, and a fine finish feed, and also includes accessoryapparatus for positioning the feed screw to grind workpiece sections ofdifferent diameters, which includes an electrically operated rotaryhydraulic motor and an electric brake coupled to the opposite ends of acommon shaft and thence through a rotary coupling and a shaft connectedto the actuating means for producing fine finish feed by rotation of thefeed screw.

Fries et al., U.S. Pat. No. 3,192,675, and patents cited therein,describe a grinding wheel feed and indicator for grinding machines.Luebkemann, U.S. Pat. No. 3,193,976 and patents therein cited, describesa grinding wheel feed system using a Nixie tube digital read-out displaypulse counter, synchronized with pulse counts generated by wheel feedingoperation, to show actual position of the wheel.

OBJECTS OF THE INVENTION It is the principal object of the invention toprovide an improved machine of a class described affording a greaterfreedom from the need for operator monitoring or to put it another way,allowing one operator to control more machines and affording highreliability and higher production rate.

It is a further object of the invention to provide a machine with fewermechanical parts consistent with the foregoing object.

It is a further object of the invention to integrate automatic andmanual control systems in machines of the class described with necessaryor desirable manual controlled operations for calibration, one-time ormaster machining, synchronizing, test, etc., carried out using theautomatic control equipment to eliminate redundant manual drives andlinkages consistent with the foregoing objects.

It is a further object of the invention to provide apparatus allowingopen loop automatic timing control of machines of the class described.

GENERAL SUMMARY OF THE INVENTION In accordance with the presentinvention, the foregoing objects are met by an improved dual cyclecamshaft grinding machine in which the wheel feed mechanism of themachine is driven along a lead screw which is rotated by anelectro-hydraulic pulse motor, comprising a servo valve driven by anelectric stepping motor to control flow of fluid to a hydraulic motor,which provides th motive power for the grinding wheel feed. An electricpulse generator provides driving pulses of selected frequency and periodto the stepping motor under control of digital control elementsincluding a counter control and a solid state machine logic controlportion which responds to feedback signals from the apparatus,indicative of cycle state, and manually fed and preset cycle limits forinitiating wheel feed and counting, but utilizes open loop numericalcontrol for ending wheel feed (and counting) steps to the extentnecessary to remove the desired amount of stock from the camshaft blank.Alternatively, the feed may be manually controlled through the samemechanical apparatus.

The related machine functions, including wheel retraction,loading/unloading work table positioning, work orientation positioning,cam indexing, etc., are also controlled by the digital control equipmentwhether on automatic cycling or in manually initiated steps. A camshaftgrinding machine utilizing the above described apparatus affordssemi-automated precision grinding, consistent with simplicity andreliability of operation, and allows a reduction in the amount ofoperator time necessary to monitor machine operation. Such a machinealso affords faster production cycles through the elimination ofunnecessary wheel retraction motions and optimum rough and finishedgrinding feed cycling, consistent with reliability. Calibration andsetup is accomplished through use of the automatic control equipment ina manual control mode without need for additional expensive handcontrols such as a hand wheel feed or the like. Compensation is providedfor ambient and wear induced shifts of operating equipment throughgaging of the workpieces allowing substantial freedom from the need foroperator monitoring. This compensation is accomplished through a postgrind size gaging of a cam base circle in comparison to a presetreference.

A transducer generates pulses as a derivative function of hydraulicservo valve operation which, in turn, is a function of originalelectrical input pulses and compares them to derive an error signalreflecting loss of synchronism.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric sketch of theessential portions of a preferred embodiment of the improved machine ofthe invention, including an electrical and hydraulic schematic diagramportions showing the various drives for machine elements.

FIG. 2 is a diagram of grinding wheel feed limiting positions and a sideview of the wheel feed assembly.

FIG. 3 is a schematic outline diagram of the hydraulic drives andcontrols of the machine.

FIGS. 4-11 are interrelated circuit diagrams for a portion of the hardwired digital logic solid state controls of the machine, FIG. 11A beingan extension of 11.

FIG. 12 is a schematic system diagram of the whole FIG. 4-11 array forconvenient viewing of all inputs and outputs together.

FIG. 13 is a circuit diagram similar to FIGS. 4-11 for auxiliaryhand/automatic selector, synchronism loss and zero reset controls of themachine.

FIG. 14 is a diagram of a post process gaging arrangement of particularutility in connection with the use of automatic loaders.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, there isshown a master camcamshaft assembly C mounted to rotate together. Agrinding wheel assembly WA including a grinding wheel W is fed into thecams spaced along the camshaft or retracted therefrom as indicated bythe double-headed arrow F. The master cam-camshaft assembly can berotated as indicated by double-headed arrow R about an axis A passingthrough a rocker bar RB which is pivotably mounted on a worktable WTwhich is longitudinally movable back and forth on a fixed base FB in adirection as indicated by the double-headed arrow L. The grinding wheelassembly includes a motor M-1 and a drive D mounted to be fed in withthe grinding wheel. The feed of the grinding wheel is accomplishedthrough a grinding wheel lead screw LS which is driven by the pulseoperated rotary hydraulic motor RHM. The hydraulic motor is connected toa source and sink of hydraulic fluid HF-l by a servo valve SV. The servovalve is driven by a stepping motor SM. A pulse generator PG providespulses of a selected frequency which is converted to usable frequenciesby a frequency divider FD. A gating digital selector control SEL thenfeeds a selected frequency train of the pulses to a translator(electronic switch) XL which in turn feeds the pulses to the steppingmotor via a stepping motor driver circuit which comprises a IO-stategenerator TSG and amplifier AMP. A rotary transducer XD is provided on,or geared to, the grinding wheel lead screw to count the number of turnsof the shaft of rotary motor RI-IM and feed a signal to a coincidencecounter circuit CC which is also connected to the output of the digitalcontroller for comparison via a position verification (nulling) circuitcontained inthe coincidence counter circuit to generate an error signal,if applicable.

The master cam-camshaft assembly C comprises a master cam array MCmounted on a spindle SP and a headstock center HS for mounting thecamshaft blank B. The rocker bar RB has a footstock FS, with a footstockcenter, for mounting the other end of the camshaft blank.

A universal drive-shaft connection U transmits power from motors M-5 orM-7 to the master camshaft assembly C via a Vee belt drive mechanism DMwhen the rocking bar has rotated the assembly C to a work position, yetallows pivoting of the rocking bar back to a loading/unloading positionalso mounted on the rocking bar RB is a steady rest SR which bearsagainst the camshaft during grinding.

Motor M5 drives the shaft U during rough grind and finish grind cyclesat speeds determined by contacts 5M and 6M, respectively, through thebelt drive. During slow finish grinding with wheel feed stopped, asdescribed below, motor M-7 drives shaft U via one-way clutch K. In therough and finish grind cycles, the clutch lets M-5 override M-7.

Initiation and cut-off of operation of electric motors and hydraulicmotors shown in FIG. 1 is controlled by circuit breakers as follows:

MOTOR CIRCUIT BREAKER M-7 M l 1M An oil cooling motor (not shown) andsimilar switching are also provided.

The above switches are controlled by corresponding relay operators(shown circles) lM, 2M, etc. and a set of master circuit breakercontacts and corresponding generator are both indicated as CRM.

Standard threephase 220 volt, 60 cycle, factory line voltage is fed inat power lines L1, L2, L3 and the above motors are connected to theselines. The voltage is stepped down to l 10 volts, single phase, 60 cycleat lines 1, 2 by transformer XF and tapped at lines 3, 4 and at linesl2, 17 all under control of master relay CRM to provide power to powersupply-signal conversion units at PS which are associated with the solidstate controls as described below.

Conventional safety interlocking is provided for the various circuitbreaker operators, CRM, 1M, 2M, etc., in well known fashion to preventdisastrous modes of machine operation.

With main circuit breakers MCB contacting to give line voltage (asindicated by a lamp, not shown) the operator pushes button PB-2 tooperate CRM which closes switch ISST and, after release of PB-2, CRMwill fashion.

The electrical pulses from the pulse generator are also fed to a digitalreadout numerical display device DRO via a driver circuit DR and anamplifier AMPl.

The electrical pulses are also fed to a counter control circuit C.C.which also has manual adjustment mechanisms for setting limits asfollows:

RRP Rough reset preset count. RSP Rough size preset count Finish resetpreset count FRP and wheel feed and retraction rates as follows:

ROU Rough grind wheel feed rate FIN Finish grind wheel feed rate REVWheel retraction rate The FSP(-finish size preseUposition is hard wired.

Referring now to FIG. 3 with cross-reference to FIG. 1 for mechanicalarrangements of parts of the FIG. 3 diagram, there is shown an hydraulicdiagram of the fluid powered portions of the machine and relatedhydraulic controls. The working fluid for all hydraulic operators,excepting wheel feed, is contained in a hydraulic tank I-IF-2 (350pounds per square inch pressure, 30 gallons capacity) which is drawn bya 5 gallon per minute pump P2 driven by motor M-2 (3l-IP, 1,200 rpm).The fluid is pumped past conventional filter, rotary valve, check valve,and relief valve structure FLT RV, CK and RLF respectively, and then toa metering device (not shown) for distribution to low pressure drives.High pressure is fed directly to table cylinder WTH via a valvecontrolled by solenoids 4BSOL and 4ASOL. High pressure is also feddirectly to the rocking bar cylinder RBI-I under control of solenoidvalve 2SOL.

Table movement is controlled through fluid pressure at hydraulic motorsSLG and SlAl-I which provide work table indexing and reversing. This isdone through the raising and lowering of the table stop lug SL driven bycylinder SLH under control of solenoid valve ISOL.

Table cushioning is provided for indexing and reversing by solenoid 3SOLwhich closes when cushioning is needed to divert fluid exhaust fromtable cylinder WTH though metering valve FCVl which slows down theexhaust to afford hydraulic cushioning.

81A is an actuating probe for limit switch LS1. The probe is depressedby work table dogs WTD during indexing to make circuit switch (whichelectrically resets 3SOL, along with outher functions described below).During table reversal, pressure to cylinder SlAH causes lowering ofprobe SlA. Limit switch LS1 is continuously made. Solenoid 3SOL isdeenergized and there is thus free hydraulic exhaust during tablereversal.

The FIG. 1 outline also indicates a series of input connections Y fromthe solid state logic control which controls auxiliary work positioningfunctions of the machine (including table position, work rotation) tothe pulser which controls termination of wheel feed. These input signalsinitiate the wheel feed in proper sequential relation to related workpositioning functions.

Inputs from the coincidence counter to the logic are indicated at X,these signals being utilized only in case of a loss of effective wheelfeed function as described below. Inputs from the machine to the logic(push button, limit switch signals, and the like) are indicated at W.Outputs from the logic to the machine (e.g., to energize solenoids) areindicated at Z.

Electric Control Systems Machine Solid State Logic FIGS. 4-11 showmachine solid state logic portions providing the control functionsreferred to in connection with the preceding general and hydrauliccomponent operating descriptions.

In these drawings reference vertical grids A1, B4, B5, etc., areprovided and cross-overs from one logic section to another are indicatedby these letters. For instance in section A of FIG. 4, a wire ends withthe notation that it connects to a wire in section F1 in FIG. 7 and inFIG. 7 a corresponding notation is found.

Referring back to FIG. 1, it will be recalled that wires 12, 17 affordpower for input devices of the machine solid state logic and that wires3, 4 afford power for the machine solid state logic output devices.

FIG. 12 shows a block diagram of the inputs and outputs of the machinelogic serially arranged. FIG. 12 should be viewed together with FIGS. 1and 3 to understand the interrelationship of electrical orelectromechanical sensors and actuators with hydraulic actuators and themachine logic section. The following operating descriptions can be readin conjunction with these systems diagrams before turning to thedetailed component apparatus and mode of operation description given inconnection with FIGS. 4-14.

The drawings of FIGS. 4-13 are, in the main, electrical circuitdiagrams. However, certain inputs are simply indicated by legend ratherthan showing the electrical input device (e.g., the source of a cyclestart signal in section Al is indicated by legend).

The components are all standard module AND or OR gates and signalconvertors indicated by the model numbers with performancespecifications currently available in catalogs of the Digital EquipmentCorporation of Maynard, Mass, but well known per se in the art andavailable from other manufacturers as well.

In some cases standard modules are ganged by connecting wires, such asA01, B01, C01, etc. Typical signal convertors are modules K578 (120V.a.c. input convertor utilizing triac maintained contact convertor), K615(isolated a.c. switch), K134 inverter. Typical AND gates are K123, K003(AND gate expander). K026 is a typical OR gate. K303 is a solid statetimer.

Those standard module references are not repeated substantially afterthe first section since like symbols in the same relative places in thelater sections indicate that the same module selection is made.

Letters D, F, H, N, etc., at terminals of the logic gates are used toindicate Boolean states e.g., D high or low, on or off, or 1 generallyreferred to as 0 or 1 for D and each other terminal for purposes ofexplaining component operation below.

The push-buttons, limit switches and relays from the machine systems ofFIGS. 1 and 3 and timer contacts from the pulser of FIGS. 1 and FIGS.4-13 below all provide inputs and outputs connected, respectively, be-

tween power lines 12 and 17 and lines 3 and 4 (note FIG. 1 for theirpower supply connections). Switches have the conventional notations intable below that NO means normally open, NC means normally closed and HCmeans held closed.

Details of the pulser are not shown since these, per se, form no part ofthe invention beyond the relation of the performance specificationstherefor as set out herein in relation to the machine system assemblyand control system sub-assembly therefor set out herein. The pulser as awhole is obtainable from several suppliers including the Dynapar Companyof Gurnee, Ill. The necessary pulser inputs and outputs are shown inFIGS. 4-13 as contacts, which are connected across the machine solidstate logic shown in the centers running vertically down FIGS. 4-11, 12and 13.

Each step motor pulse moves the wheel slide assembly WA 0.0001 inchesaffording a stock removal of 0.0002 inches (on a diameter basis) on thedisplay. The rough grind feeding rate is adjustable from 0 to 1,999pulses per second (0l2 inches per minute advance) and the finishgrinding feed rate is adjustable from 0 to 99 pulses per second (0-0.6inches per minute). As shown in FIG. 1 these settings are made by manualsettings at the counter control. The slide return rate of assembly WA isfixed at 2,000 pulses per second (12 inches per minute). Provision ismade for manually picking" the wheel assembly forward in 0.0001 inch(one pulse) increments. The pick increments do not register on thecounting means of the pulser and do not appear on display DRO.

Failure of the motor RI-IM to follow command pulses of the pulser isdetected by rotary transducer XD, preferably set to give an error signalat the circuit C.C. whenever a loss of synchronism in excess of plus orminus counts (i 0.008 inches) occurs.

The plus or minus 80 counts following limit does not reflect an absolutesynchronism error, but rather includes an allowance for time lag betweenelectrical pulse increment accumulation generated by the pulser andelectrical pulse increment accumulation generated by the rotarytransducer as a function of mechanical output shaft motion. Upontermination of electrical output, the mechanical output shaft, and hencetransducer generated pulses, can catch up.

At each preset station described above i.e., RSP, RRP, FRP, FSP totalpulses of the transducer and pulser are compared (after a time delay toallow catchup) and if there is a difference greater than plus or minuseight counts a positional error signal is generated.

The error signal generated in either the following or positional modesis preferably utilized to swtch the machine from automatic into handmode and/or to generate a visual indication of the error (or audiblealarm).

The digital read-out display DRO provides a continuous indication ofdistance of the wheel from a hardwired preset zero which, after setup asdescribed below, corresponds to FSP. During grinding the DRO is thusshowing the amount of stock which remains to be removed from thecamshaft blank surface.

The pulser may also include wheel wear compensator presets activatedeach time wheel truing is scheduled or occurs to shift the reset presetend limits by an amount corresponding to the known wheel radiusreduction produced by truing.

Operation Operation is initially described in terms of the machinesystem as a whole, then redescribed in terms of specific componentfunctions.

' BasicAutomatic Dual Cycle Wheel Feed In accordance with theconventional practice, the grinding wheel is fed in to do a roughgrinding cycle on each cam, with the table indexing longitudinallybetween rough grinding cycles on each cam to present the next cam forrough grinding. Referring now to FIG. 2, the grinding wheel is shownwith respect to the camshaft at a moment in time when it is in theprocess of finishing cam number one (No. l) of a series of cams on thecamshafts. Limiting positions of the grinding wheel are indicated bychain lines and the dimension lines RRP, FRP, RSP, FSP. The wheel startsout with its leading edge at position RRP the rough reset presetposition. The wheel is advanced in to accomplish rough grinding reachingrough size RSP preset position at the completion of rough grinding. Thewheel then backs off to rough reset preset. The cams are longitudinallyindexed and the wheel then moves in to rough grind the next cam, etc.After completion of rough grinding of all the cams, the wheel is backedoff to the finished reset preset position FRP. It advances to the finishsize preset position FSP to finish the cam, then after die-out(described below), backs off to F RP again and as the table is indexed,moves in to finish the next cam, etc. At the moment shown in thedrawings cam number two (No. 2) which is seen behind cam number one hasbeen rough ground and will be next in turn for finished grinding. Forpurposes of setting up the controls, the position FSP is generally takenas a zero position. The RSPan FRP position controls are adjustablebetween 0.0000 and 0.9998 inches and the RRP position is adjustablebetween 0.0000 and 0.9998 inches, in

increments of 0.0001. A typical set of controlled dimensions is that thedistance from FSP to RSP will be 0.007 inches, the distance from FSP toFRP will be 0.022 inches and the distance from FSP to RRP will be 0.150inches. Typically, the wheel is a 24 inch diameter wheel of vitrifiedbond type (e.g., model 51A60M- VBEXl 13C of Norton Company). Its speedis 12,000 surface feet per minute, achieved by rotation of 1,900revolutions per minute. The feed rate for the wheel during roughgrinding is typically 1.2 inches per minute and during finish grindingis fifty thousandths (0.050) of an inch per minute. The rough grindwheel feed rate is adjustable between zero and 12 inches per minute andthe finish grind wheel feed rate is adjustable between zero and 0.6inches per minute.

At the end of each finish grinding cycle for each cam, the wheel doesnot immediately retract but with wheel feed stopped (i.e., feed rateequals zero inches per minute), the work has six die out turns with aninitial three turns at a fast finish rate of 75 revolutions per minuteand three turns at a slow finish rate of 38 revolutions per minute whilethe wheel continues at full speed.

After rough grinding all the cams of a given shaft, the wheel isreturned to finish reset preset position for dressing by a dressingtool. Then all of the cams are finish ground in a cycling similar tothat of rough cycling except that movement of the wheel is forward frompoint FRP to FSP during grinding and retracted from FSP to FRP betweengrinding operations and allowing the work table to index. After allfinishing is completed, the wheel goes back to its rough reset positionRRP where it is dressed while the table goes to a load position. Thefinished camshaft is unloaded. A new rough camshaft is put in andcycling is repeated as just described with the exception that theinitial calibration movement is not necessary. Automatic controls arealso provided in connection with the loading and moving of the table tothe beginning of roughing. The automatic control also controls therocking bar to move it to and from working position during all of theabove described grinding wheel cycling, controls table indexing and alsocontrols truing and lubrication operations and work rotation.

During the basic cycling described above, the wheel feed and workrotation counters control timing of the various steps of operation.During rough grinding the pulse counter counts down to when it coincideswith RSP and sends a wheel retraction index signal. During finishgrinding, machine logic initiates the pulse counter. The pulse countercounts down to zero, which is FSP, then sends a signal to activate thework rotation controller which counts out the die-out turns, thensignals for wheel retract and table index. When the last cam isfinished, the wheel is returned to RRP through an operating signalinitiated by a position sensing limit switch via the machine logichereinafter described.

Backlash takeup during finish grinding is accomplished at rough grindfeed rates. Provision is made in the finish cycle counting apparatus andfeed rate controls to count out a number of pulses while running atrough grinding feed rate (generally to take up about 0.015 inch backlashor greater or less backlash associated with a particular machine; thebacklash is measured and the allowance is preset).

Initial Calibration Operation When beginning to machine the series ofcamshaft blanks the operator sets up the master cam spindle, measuressome of the camshaft blanks and determines the approximate amount ofstock to be removed. He loads a camshaft blank between headstock andfootstock of the master cam-camshaft assembly. He determines anapproximately RRP (rough reset preset)size and inserts that that numberinto the control means via the counter control. He sets rough cycle andfinish cycle wheel feed rates. Wheel retraction rate is fixed in themachine. He sets rough, finish and slow finish work rotation rates.

The operator then works a table control lever to index the work table toalign the first cam position on the camshaft with the grinding wheel(and with the cam follower). The operator then pushes a cycle startbutton PB-9 and PB-IO (FIG. 13) to lower the rocking bar (and bringmaster cam one against the follower while cam one of the work is inworking position).

Interlocks normally preventing wheel feed are released by table indexingto the first cam position and

1. An improved machine for grinding camshaft blanks or the like,comprising in combination: a work table means movable in a longitudinaldirection parallel to a characteristic long dimension of the work table,b. rocking bar means mounted on said table and comprising a rotatablework support and rotatable master cam spindle, having a plurality ofannular cam shapes thereon, mounted on a rocker bar along a common firstaxis parallel to the direction of longitudinal movement of the table,and motive power means for moving said work into engagement with amaster cam follower and away therefrom, c. means for driving saidspindle and work support rotatably at seleCted fast and slow speeds ofrough cycle work and a slow speed of finish work, d. grinding meanscomprising at least one grinding wheel and electric pulse motor meansfor feeding said wheel along a second direction perpendicular to saidfirst direction inwardly to and outwardly from the work area defined bythe work support at selected fast and slow speeds and means for rotatingthe wheel at selected speeds, e. electrical control means forcontrolling the feed of the wheel from a rough reset preset position,inwardly to rough size preset position, then outwardly to said roughreset preset position, then inwardly again to said rough size presetposition and the outwardly to said rough reset preset position, cyclingbetween said rough reset preset position and rough size preset positionthrough a series of cycles, and controlling wheel feed to have saidwheel similarly cycle between a finish reset preset position and afinish size preset position in a series of cycles and comprising anelectrical pulse generator and means for selecting desired pulse speedrates therefrom to operate the said electric pulse motor as a functionof a selected frequency of the applied pulses thereby producing aselected number of incremental wheel advance movements, means forcounting pulses so processed and means for presetting said pulsecounting means, f. electrical control means for operating said rockingbar means, g. electrical control means for operating said work supportrotator, h. electrical control means for operating said work tabledrive, i. logic means interconnecting said pulse counter and electricalcontrol means (f) (g) (h) to automatically cycle the work through roughgrinding of all cam shapes on the work, then finish grinding and die-outgrinding of all cams on the work, with each rough or finish grindproceeding until the pulse counter counts out the number of presetpulses for said rough or finish cycle, respectively, to provide therebyan open loop controlled rough and finish grinding wheel feed and workrotation,
 2. The apparatus of claim 1 further comprising, manualoperating controls for carrying out the steps of machine movement, saidmanual operating controls being operatively connected to said logicmeans to operate said counter and control means via said logic means,and manual/automatic switching means for selectively setting said logicmeans to selectively operate in manual and automatic modes.
 3. Theapparatus of claim 1 further comprising pick means for providing a smallnumber of pulses for moving the wheel in small single increments ofmotion each time such pick means are actuated without changing the pulsecount setting.
 4. The apparatus of claim 3 wherein said pick means aremanually actuatable.
 5. The apparatus of claim 3 further comprising postgrinding work size measuring means connected to said pick means andconstructed and arranged to actuate same in response to variation from apreset reference size in the work to reduce such variation in the nextgrind.
 6. The apparatus of claim 5 wherein said pick means areselectively manually actuatable.
 7. The apparatus of claim 3 whereinsaid pick means are manually actuatable.
 8. The apparatus of claim 1further comprising post grinding work size measuring means for measuringfinish work size and comparing work size to a preset reference size andproviding a usable differential signal.
 9. The apparatus of claim 7wherein said means producing said differential signal are constructedand arranged to reset the zero finish size without disturbing the pulsefeeding arrangement.
 10. The apparatus of claim 8 in combination withautomatic loading means.
 11. The apparatus of claim 1 in combinationwith means for measuring operation of said step form output operator andgenerating a count of servo valve operations and comparing the same withthe corresponding electrical pulse counts for coincidence within preseterror limits, and means to stop wheel feed operation in response to aloss of synchronism between the original electrical and derivativemechanical pulses beyond said preset limit.